During the manufacture of a semiconductor device or a liquid-crystal display (LCD), a resist pattern is generally formed by coating the surface of a substrate with a resist solution, then exposing the substrate to light using a required mask, and developing the substrate. In this case, the resist pattern is formed by a system that comprises a coating and developing apparatus which performs the coating process and developing process discussed above, and an exposure apparatus that is connected to the coating and developing apparatus and performs the exposure process discussed above.
Lithography for exposing a substrate to light with a liquid layer formed on the surface of the substrate in order to penetrate the light is present as the exposure technique used in the exposure apparatus of the above system. Hereafter, such an exposure technique is referred to as “liquid-immersion photolithography.”
As shown in FIG. 10, such liquid-immersion photolithography uses the exposure means 1 that includes a supply port 11, a suction port 12, both provided in a peripheral section of the exposure means, and a lens 10 provided centrally therein. That is to say, pure water is supplied from the supply port 11 of the exposure means 1 to the surface of a wafer W, then the pure water is recovered via the suction port 12, and thus a liquid membrane (pure-water membrane) is formed between the surfaces of the lens 10 and the wafer W. Under this state, the wafer W is next illuminated with light via the lens 10. After this, the exposure means 1 is slid in a lateral direction to sequentially transfer required circuit patterns to the surface of the wafer W.
In the foregoing liquid-immersion photolithography, after the wafer W has been coated with a resist solution, a water-repellent protective film is formed on the surface of the wafer W in the protective-film coating module of the coating and developing apparatus before the liquid-immersion light exposure is performed. This protective film is formed to suppress the dissolution of the resist and to make it unlikely for the resist to remain on the surface of the wafer W during the liquid-immersion light exposure. Before the resist solution is developed following completion of the liquid-immersion light exposure, the protective film is removed in the protective-film removing module of the coating and developing apparatus (refer to JP-A-2006-229183).
Meanwhile, the coating and developing apparatus of the above system also has an inspection module. Before the liquid-immersion light exposure is performed, this inspection module inspects whether the protective film is appropriately formed on the entire surface of the wafer during the above film-forming process. If, during the inspection of the wafer surface by the inspection module, the protective film is judged not appropriately formed on the wafer surface, this wafer (hereinafter, referred to as a defective wafer) needs to be returned to an associated carrier without being subjected to the liquid-immersion light exposure. Examples of such a defective wafer include a wafer that has a protective film formed on the entire surface but has the protective film extending so far as to reach the edge, or a wafer that has a section(s) on the surface where the protective film is not formed.
For example, if the liquid-immersion light exposure is performed upon a wafer having a protective film adhering to the edge, when the wafer is held in a transfer arm, the film at the edge peels off at the contact surface. As a result, the film that has peeled off diffuses foreign matter, thus contaminating the wafer, the lens, and the like. In addition, if the liquid-immersion light exposure is performed upon a wafer that has a section(s) where the protective film is not formed on the surface thereof, the resist on the wafer dissolves and adheres to the surface of the lens 10 of the exposure means 1 shown in FIG. 10. The resist that has thus adhered damages the lens 10 and shortens the service life of the exposure apparatus.
It is described in JP-A-2005-32770 that an abnormal substrate, such as a substrate on which resist coating has failed, is queued in the buffer of an interface unit. It is also described that after the substrate immediately preceding the abnormal substrate has been unloaded from the exposure apparatus, the abnormal substrate is carried to a required module, as with the normal substrate, and that after being carried to the module, the abnormal substrate is not processed in the module.
However, if the abnormal substrate falls into the category of the defective wafers discussed above, since a protective film is already formed on the surface of the defective wafer which has been returned to the carrier, reusing this wafer requires removing the protective film formed on the surface of the wafer. The protective film is removed by a protective-film removing device provided separately from the coating and developing apparatus. For this reason, independent carriage only of the defective wafer to the protective-film removing device is necessitated and subsequent process operations become troublesome.
Patent Document 1: JP-A-2006-229183
Patent Document 2: JP-A-2005-32770